1. Field of the Invention
The invention relates to lasers and, more particularly, to a configuration of portable laser head.
2. Prior Art Discussion
The trend towards compactness, ruggedness, structural simplicity and reliability has been accompanying development of lasers since the inception of the laser industry. Portable or hand-held low-power laser heads are typically, but not necessarily, associated with lasers capable of generating light at wavelengths in visible spectrum, such as green, yellow and others, and near infra-red ranges.
FIG. 1 shows an exploded view of a rather typical portable laser head 10. A light source emits, for example, a near IR light coupled to and guided along a fiber which is enclosed in a housing 14. The fiber is held in an input collimator assembly aligned to the housing 14. As known to one of ordinary skills in the laser arts, a typical collimator assembly includes a fiber, a glass tube or capillary holding the exposed fiber end, and a lens, such as a graded-index (GRIN) lens. The light exiting the fiber end is collimated by a GRIN before it enters a frequency converter holder 16. The holder 16 is configured to house a nonlinear optical element, such as a crystal, operative to convert the collimated input light to light of other desirable frequencies. The frequency conversion rate is not high. As a consequence, the output light exiting the crystal carries desirable and undesirable wavelengths when it impinges upon a beam splitter 18 located outside the housing of holder 16 along a light path. To transmit light at the desired wavelength and reflect light at undesired wavelengths, the surface of beam splitter 18 has a coating.
One of the requirements to be met by laser head 10 includes a compact configuration. Mounting beam splitter 18 outside crystal holder 16 contributes to enlarging the overall configuration of the laser head.
Returning to the configuration of splitter 18, the reflected light adds to the heating of laser head 10 and has to be evacuated therefrom. A dump collimator assembly or unit 20, shown in FIG. 1, is operative to remove the reflected light from laser head 10.
Turning to FIG. 1A, dump collimator assembly 20 receives the reflected light from beam splitter 18. The dump collimator assembly 20 includes a dump collimator 22 which is mounted inside crystal holder 16. The dump collimator 22 is configured with a 45° mirror 24 training the light, which is reflected from splitter 18, at a ball lens 26 which focuses the light so that it enters an output fiber guiding the reflected light outside laser head 10.
The combination of beam splitter 18 and mirror 24 poses a few problems. One of the problems relates to adjustment of beam splitter 18 relative to crystal holder 16. The other problem stems from difficulties experienced during alignment of beam splitter mirror 18 and mirror 24.
It is, therefore, desirable to provide a portable laser head having a crystal holder configured so as to house a beam splitter and a dump collimator.
It is also desirable to provide a portable laser head configured so that a beam splitter and a mirror of dump collimator are mounted in a crystal holder in a fixed spatial relationship relative to one another.
It is further desirable to provide a portable laser head which is relatively inexpensive and compact.